Overall prognosis worse for those patients

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Patients with primary biliary cirrhosis associated with Sjögren's syndrome (PBC-SS) have a higher risk of developing interstitial lung disease and spontaneous bacterial peritonitis, and have lower survival than patients with PBC alone.

Data indicate that aggressive surveillance of thyroid and pulmonary functions is necessary for patients with concomitant PBC-SS.

Patients who suffer from primary biliary cirrhosis/cholangitis (PBC) have a higher risk of developing interstitial lung disease and spontaneous bacterial peritonitis if their condition is associated with Sjögren's syndrome, according to researchers in Taiwan.

In a retrospective study of patients diagnosed with PBC over a 15-year period, researchers led by Chun-Ting Chen, MD, of the Tri-Service General Hospital, National Defense Center in Taipei, also determined that PBC patients with Sjögren's have overall lower survival than patients who only have PBC.

Autoimmune disorders such as Sjögren syndrome are believed to be associated with PBC, with an incidence rate in PBC patients ranging from about 20% to 80%. Sjögren's often involves the lacrimal and salivary glands, and in the course of the disease also involves the lungs, kidneys, cardiovascular system, central nervous system, and liver.

However the effect on the clinical outcomes of PBC is uncertain, and in this study the researchers wanted to compare the clinical differences in long-term outcomes between PBC-only patients and PBC patients with concomitant Sjögren's (PBC-Sjögren).

Accordingly, they recorded major events that occurred during the observation period, including the incidence of hepatocellular carcinoma, end-stage renal disease, variceal bleeding, hypothyroidism, interstitial lung disease (ILD), spontaneous bacterial peritonitis (SBP), and death.

ILD comprises a large group of disorders characterized by progressive scarring of the lung tissue between and supporting the air sacs and, according to Mayo Clinic, may cause progressive lung stiffness affecting the ability to breath and get enough oxygen into the bloodstream.

SBP is an acute bacterial infection that is a common and potentially life-threatening complication of cirrhosis.

The researchers identified 136 patients with PBC who were classified into two groups -- those with concomitant Sjögren's and those without. (Patients with diabetes, hypertension, advanced liver cirrhosis at initial diagnosis of PBC, and other liver diseases were excluded.) In this study the incidence of Sjögren's in PBC was 35.3%.

Chen and his colleagues found that the incidence of ILD was "significantly" higher in PBC-Sjögren patients (20.8%) than in PBC-only patients (3.9%) (P=0.005). They also found that the incidence of SBP "significantly" increased in PBC-Sjögren patients (25.0%) compared with PBC-only patients (5.2%) (P =0.002).

The researchers also determined that the incidence of hepatocellular carcinoma, end-stage renal disease, variceal bleeding, and hypothyroidism were all higher in the PBC-Sjögren group than in the PBC-only group, but that the differences weren't significant.

During the course of study period Chen and his colleagues determined that overall mortality rate for the PBC-only group (5.2%) appeared to be significantly lower than the overall mortality rate for the PBC-Sjögren group (18.8%) (P=0.031).

They also found that ILD appeared to be a more common cause of death in the PBC-Sjögren group than the PBC-only group. However, the incidence is low, they wrote, adding that longer observation times and larger studies are needed to analyze the relationship between ILD and death in PBC-Sjögren patients.

The researchers concluded that their study suggests that PBC-Sjögren patients have a higher risk of developing ILD and SBP and have a poorer prognosis than those patients without concomitant Sjögren syndrome. "Aggressive surveillance of thyroid and pulmonary functions should therefore be performed in these patients," they wrote.

There were several limitations to the study.

For example, Chen and his colleagues pointed out that the study is retrospective and not a randomized control trial and therefore could be subject to some unexpected bias.

Additionally, "the observation time was short and sample size small; longer follow-up studies with larger sample sizes should allow for observation of more significant differences such as in the incidence of hypothyroidism, between the PBC-Sjögren and PBC-only groups," they wrote.

They suggested that long-term prospective studies should be carried out to evaluate the clinical characteristics and differences in outcomes between the two sets of patients.

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